Operating system for a direct antifreeze cooled fuel cell power plant

Abstract

An operating system for a direct antifreeze cooled fuel cell power plant is disclosed for producing electrical energy from reducing and process oxidant fluid reactant streams. The system includes at least one fuel cell for producing electrical energy from the reducing and oxidant fluid streams; fuel processing components for processing a hydrocarbon fuel into the reducing fluid; a thermal management system that directs flow of a cooling fluid for controlling heat within the plant including a porous water transport plate adjacent and in fluid communication with a cathode catalyst of the fuel cell; a direct antifreeze solution passing through the water transport plate; and, a split oxidant passage that directs the process oxidant stream into and through the fuel cell.

What is claimed is:  
     
       1. An operating system for a direct antifreeze cooled fuel cell power plant that generates electrical energy from reducing fluid and process oxidant reactant streams, the operating system comprising: 
       a. at least one fuel cell means for producing electrical energy from the reducing fluid and process oxidant streams including an electrolyte secured between an anode catalyst and a cathode catalyst;  
       b. fuel processing component means including a burner that receives an anode exhaust stream from an anode exhaust passage secured between an anode flow field adjacent the anode catalyst and the burner and a reformer means in fluid communication with the fuel cell means for processing and reforming a hydrocarbon fuel into the reducing fluid;  
       c. a thermal management system means for controlling temperature within the power plant including a porous water transport plate secured in direct fluid communication with the cathode catalyst;  
       d. a direct antifreeze solution passing through the thermal management system for cooling the fuel cell means, wherein the direct antifreeze solution is an organic antifreeze solution that does not wet the cathode catalyst and that is non-volatile at cell operating temperatures; and,  
       e. a split oxidant passage means for directing the process oxidant stream into and through the fuel cell means, for directing a reformer feed portion of the process oxidant stream through a reformer feed branch of the split oxidant passage to the fuel processing component means, and for directing an exhaust portion of the process exhaust stream through an exhaust branch of the split oxidant passage into a plant exhaust passage.  
     
     
       2. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 1 , wherein the direct antifreeze solution is an alkanetriol direct antifreeze solution. 
     
     
       3. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 1 , wherein the direct antifreeze solution is an alkanetriol direct antifreeze solution selected from the group consisting of glycerol, butanetriol, and pentanetriol. 
     
     
       4. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 1 , wherein the direct antifreeze solution is a special direct antifreeze solution having; 
       a. a freezing point of at least −20° F.;  
       b. a surface tension greater than 60 dyne/cm at an operating temperature of the fuel cell;  
       c. a partial pressure of antifreeze above the solution at the cell operating temperature that is less than 0.005 mm Hg; and,  
       d. a capacity of being oxidized by the anode and cathode catalysts at fuel cell voltages.  
     
     
       5. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 1 , wherein the plant includes a pressure control means for maintaining a positive pressure differential between the reactant streams passing through the fuel cell means and the direct antifreeze solution passing through the porous water transport plate so that the reactant streams within the fuel cell are at a greater pressure than the direct antifreeze solution within the water transport plate. 
     
     
       6. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 1 , wherein the split oxidant passage includes a first reformer feed branch that directs a first reformer feed portion of the process oxidant stream from an inlet branch of the split oxidant passage between an oxidant inlet and the fuel cell means to the burner. 
     
     
       7. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 6 , wherein the split oxidant passage includes a second reformer feed branch that directs a second reformer feed portion from the exhaust branch of the split oxidant passage between the fuel cell means and the plant exhaust passage to the burner. 
     
     
       8. An operating system for a direct antifreeze cooled fuel cell power plant that generates electrical energy from reducing fluid and process oxidant reactant streams, the operating system comprising: 
       a. at least one fuel cell means for producing electrical energy from the reducing fluid and process oxidant streams including an electrolyte secured between an anode catalyst and a cathode catalyst;  
       b. fuel processing component means including a burner that receives an anode exhaust stream from an anode exhaust passage secured between an anode flow field adjacent the anode catalyst and the burner and a reformer means in fluid communication with the fuel cell means for processing and reforming a hydrocarbon fuel into the reducing fluid;  
       c. a thermal management system means for controlling temperature within the power plant including a porous water transport plate secured in direct fluid communication with the cathode catalyst;  
       d. a direct antifreeze solution passing through the thermal management system for cooling the fuel cell means, wherein the direct antifreeze solution is an organic antifreeze solution that does not wet the cathode catalyst and that is non-volatile at cell operating temperatures;  
       e. a split oxidant passage means for directing the process oxidant stream into and through the fuel cell means, for directing a reformer feed portion of the process oxidant stream through a reformer feed branch of the split oxidant passage to the fuel processing component means, and for directing an exhaust portion of the process exhaust stream through an exhaust branch of the split oxidant passage into a plant exhaust passage; and,  
       f. a direct mass and heat transfer device means secured in fluid communication with both an oxidant inlet that directs the process oxidant stream into the fuel cell means and also with the plant exhaust passage that directs a plant exhaust stream out of the fuel cell means for directly transferring mass and heat exiting the plant from the plant exhaust stream into the plant within the process oxidant stream, the direct mass and heat transfer device including a mass transfer medium means for sorbing a polar fluid substance consisting of polar molecules within the plant exhaust stream and for desorbing the polar substance into the process oxidant stream, the mass transfer medium means being supported by a separator housing in mass transfer relationship between the oxidant and exhaust streams.  
     
     
       9. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 8  wherein the mass transfer medium means includes the direct antifreeze solution as a liquid transfer medium supplied through a liquid transfer medium feed line from the thermal management system means. 
     
     
       10. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 9 , wherein a maximum system exhaust temperature for operation of the operating system in water balance is determined by the formula; 
       
         
           TEX=1,000/((2.85528−(2.85528 2 −(4×(−0.34911)×(6.1893−LOG 10 (14.696/(7.14/UO 2 +0.5)/MFW)))) 0.5 )/(2×(−0.34911)))−460;  
         
       
       where “TEX” is a maximum system exhaust temp. °F., where “UO 2 ” is a system air utilization, and where “MFW” is a mole fraction of water for the direct antifreeze solution. 
     
     
       11. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 9 , wherein the direct antifreeze solution is an alkanetriol direct antifreeze solution. 
     
     
       12. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 9 , wherein the direct antifreeze solution is an alkanetriol direct antifreeze solution selected from the group consisting of glycerol, butanetriol, and pentanetriol. 
     
     
       13. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 9 , wherein the direct antifreeze solution is a special direct antifreeze solution having; 
       a. a freezing point of at least −20° F.;  
       b. a surface tension greater than 60 dyne/cm at an operating temperature of the fuel cell;  
       c. a partial pressure of antifreeze above the solution at the cell operating temperature that is less than 0.005 mm Hg; and,  
       d. a capacity of being oxidized by the anode and cathode catalysts at fuel cell voltages.  
     
     
       14. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 8 , wherein the plant includes a pressure control means for maintaining a positive pressure differential between the reactant streams passing through the fuel cell means and the direct antifreeze solution passing through the porous water transport plate so that the reactant streams within the fuel cell are at a greater pressure than the direct antifreeze solution within the water transport plate. 
     
     
       15. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 8 , wherein the split oxidant passage includes a first reformer feed branch that directs a first reformer feed portion of the process oxidant stream from an inlet branch of the split oxidant passage between an oxidant inlet and the fuel cell means to the burner. 
     
     
       16. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 15 , wherein the split oxidant passage includes a second reformer feed branch that directs a second reformer feed portion from the exhaust branch of the split oxidant passage between the fuel cell means and the plant exhaust passage to the burner. 
     
     
       17. An operating system for a direct antifreeze cooled fuel cell power plant that generates electrical energy from reducing fluid and process oxidant reactant streams, the operating system comprising: 
       a. at least one fuel cell means for producing electrical energy from the reducing fluid and process oxidant streams including an electrolyte secured between an anode catalyst and a cathode catalyst;  
       b. fuel processing component means including a burner that receives an anode exhaust stream from an anode exhaust passage secured between an anode flow field adjacent the anode catalyst and the burner and a reformer means in fluid communication with the fuel cell means for processing and reforming a hydrocarbon fuel into the reducing fluid;  
       c. a thermal management system means for controlling temperature within the power plant including a porous water transport plate secured in direct fluid communication with the cathode catalyst;  
       d. a direct antifreeze solution cooling fluid passing through the thermal management system for cooling the fuel cell means, wherein the direct antifreeze solution is an organic antifreeze solution that does not wet the cathode catalyst and that is non-volatile at cell operating temperatures;  
       e. a split oxidant passage means for directing the process oxidant stream into and through the fuel cell means, for directing a reformer feed portion of the process oxidant stream through a reformer feed branch of the split oxidant passage to the fuel processing component means, and for directing an exhaust portion of the process exhaust stream through an exhaust branch of the split oxidant passage into a plant exhaust passage; and,  
       f. a fuel processing thermal exchange loop means including a heat exchanger secured in heat exchange relationship with reformed fuel heated by a selective oxidizer of the fuel processing component means for passing a second cooling fluid through the heat exchanger to remove heat from the reformed fuel.  
     
     
       18. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 17 , wherein the fuel processing thermal exchange loop means further comprises a coolant-coolant heat exchanger secured in heat exchange relationship with the thermal management system means that directs the second cooling fluid in heat exchange relationship with the direct antifreeze solution cooling fluid. 
     
     
       19. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 17 , wherein the direct antifreeze solution is an alkanetriol direct antifreeze solution. 
     
     
       20. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 17 , wherein the direct antifreeze solution is an alkanetriol direct antifreeze solution selected from the group consisting of glycerol, butanetriol, and pentanetriol. 
     
     
       21. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 17 , wherein the direct antifreeze solution is a special direct antifreeze solution having; 
       a. a freezing point of at least −20° F.;  
       b. a surface tension greater than 60 dyne/cm at an operating temperature of the fuel cell;  
       c. a partial pressure of antifreeze above the solution at the cell operating temperature that is less than 0.005 mm Hg; and,  
       d. a capacity of being oxidized by the anode and cathode catalysts at fuel cell voltages.  
     
     
       22. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 17 , wherein the plant includes a pressure control means for maintaining a positive pressure differential between the reactant streams passing through the fuel cell means and the direct antifreeze solution passing through the porous water transport plate so that the reactant streams within the fuel cell are at a greater pressure than the direct antifreeze solution within the water transport plate. 
     
     
       23. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 17  wherein the split oxidant passage includes a first reformer feed branch that directs a first reformer feed portion of the process oxidant stream from an inlet branch of the split oxidant passage between an oxidant inlet and the fuel cell means to the burner. 
     
     
       24. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 23 , wherein the split oxidant passage includes a second reformer feed branch that directs a second reformer feed portion from the exhaust branch of the split oxidant passage between the fuel cell means and the plant exhaust passage to the burner. 
     
     
       25. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 17 , further comprising a direct mass and heat transfer device means secured in fluid communication with both an oxidant inlet that directs the process oxidant stream into the fuel cell means and also with the plant exhaust passage that directs a plant exhaust stream out of the fuel cell means for directly transferring mass and heat exiting the plant from the plant exhaust stream into the plant within the process oxidant stream, the direct mass and heat transfer device including a mass transfer medium means for sorbing a polar fluid substance consisting of polar molecules within the plant exhaust stream and for desorbing the polar substance into the process oxidant stream, the mass transfer medium means being supported by a separator housing in mass transfer relationship between the oxidant and exhaust streams. 
     
     
       26. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 25 , wherein the mass transfer medium means includes the direct antifreeze solution as a liquid transfer medium supplied through a liquid transfer medium feed line from the thermal management system means. 
     
     
       27. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 25 , wherein the mass transfer medium means comprises an enthalpy exchange barrier including a support matrix means defining hydrophillic pores having a pore-size range of between 0.1-100 microns for supporting a liquid transfer medium. 
     
     
       28. The operating system for a direct antifreeze cooled fuel cell power plant of  claim 17 , wherein the system further comprises a water treatment system means for treating the direct antifreeze solution, including a demineralizer secured in fluid communication with the thermal management system through a demineralizer feed line and return line secured to the thermal management system for passing the direct antifreeze solution through the demineralizer, and including a degasifier means secured in mass transfer relationship between the thermal management system and an oxidant inlet that directs the process oxidant into the fuel cell for removing dissolved contaminants in the direct antifreeze solution.